This article first appeared in the July-August 2007 issue of the New Oxford Review, and is reprinted with permission. New Oxford Review, 1069 Kains Ave., Berkeley CA 94706, U.S.A., www.newoxfordreview.org.

While controversy swirls around whether Intelligent Design theory can somehow indicate God’s existence, we ought not to forget that Catholic tradition has always held that God’s existence can be known by the light of unaided reason, and this, by metaphysical not empirical, scientific argument. Still, even knowing that God exists, many people today fear that there is inherent conflict between the scientific claims of evolutionary theory and the Genesis account of Adam and Eve. Seeking to find a scientific foundation for Genesis, many Christians have embraced the young-earth creationist movement that (1) rejects evolution theory, and (2) insists that mankind is perhaps 6,000 years old and the universe some 10,000 years old – consistent with a literalist reading of the patriarchal genealogies found in the Book of Genesis.

Still, the vast majority of mainstream natural scientists maintain that (1) evolution theory is factual, (2) the cosmos is some 12 to 15 billion years old, (3) life on earth goes back nearly four billion years, and (4) man himself gradually evolved over millions of years. Thus, many Christians today wonder how to reconcile their general acceptance of mainstream science with belief in Adam and Eve’s historicity. While many liberal theologians see little need for Adam and Eve to be a single pair of first parents, authentic Catholics and many traditional Protestants understand that theological monogenism -- which holds that all mankind is descended from a single pair of ancestors -- must be maintained in order to confirm the reality of Original Sin, and the consequent need for the Redeemer. My book Origin of the Human Species is a philosophical work on evolution in which I offer a detailed explanation of how the current theory of human evolution might be fully consistent with sound scriptural interpretation.

If we don’t know what constitutes genuine human nature, then there is no way to detect when and how true man first appeared. Philosophical psychology is the science that studies human nature and tells us how it distinguishes us from lower brute animals. Animals can experience sensations, such as color, shape, sound, movement, touch, and so forth. Man can do all that, plus he has intellective knowledge and free will. Because man possesses an intellective spiritual soul, he can understand the natures of things, make judgments, and reason. Thus, while animal cognition is forever bound to the singular and concrete sense experiences of its immediate surroundings, human intellective knowledge transcends sensation to grasp the universal truths of the cosmos itself, write poetry, erect civilizations, and investigate science and theology. Man alone consciously reflects on the meaning of his own existence and writes articles about his possible evolutionary origins.

Animals can make tools. Perhaps the most famous example of primate tool-making abilities is the “termite-fishing” chimps reported by Jane Goodall. These clever African primates break off grass reeds and carry them some distance to termite mounds, where incautious termites will crawl onto the reeds inserted into their mounds – quickly becoming food for the chimps. Such behavior, and others like it, though impressive, can be explained in terms of environmental “programming.” The chimps can initially learn the behavior by happy accident followed by habit formation reinforced by the pleasurable outcome. Transmission to the rest of the colony arises from simple imitation. Some anthropologists, including Goodall, appear unaware of widespread animal tool use -- for example, sea otters and a Galapagos finch that routinely use rocks to obtain food, spiders that use throw nets, or even the universal propensity of birds to make nests as egg-holding devices.

Especially in the case of primates, large brains and sophisticated external and internal senses can enable higher animals to use sense powers to fashion rudimentary tools. Still, tools whose fashioning is determined by mere usefulness grounded in immediate sensible rewards can arise from such things as trial and error, imagination, memory, and shape recognition. Though impressive, such artifacts need not transcend the abilities of animals lacking intellective powers.

The most intriguing claims for lower primates’ “intelligence” arise from their famed ability to learn sign languages we teach them. But such impressive activities can be explained by the internal senses of instinct, imagination, and memory combined with mechanisms, such as intense training, image association, rapid signing to obtain sensible rewards, unintentional cuing, and unavoidable human influence.

The evidence against animal intellective ability is scarcely debatable. In the wild – without any human influence – brute animals, including lower primates, fail (1) to develop genuine language with ever-increasing vocabulary, (2) to make genuine progress, as is so evident in human society, (3) to show understanding of cause and effect, not merely remembered association of images, and (4) to show knowledge of immaterial objects. This last is manifested in man’s obviously unique understanding of abstract objects in science and religious belief. If lower animals possessed intellect, they should have developed all four of these abilities on their own. Showing none of them proves their lack of true intellect. In Origin of the Human Species, I examine recent ape-language research, offering far more detailed evidence of the preceding claims than present space permits.

While lower primates appear able to fashion rudimentary tools, true humans’ first presence must be evinced by artifacts that intellect alone can produce – objects showing genuine understanding of abstract concepts. In which hominid population might such artifacts be found?

No single scenario for human origins gains total support from all paleoanthropologists. In general, current human evolutionary theory traces back our origins from earlier tree-dwelling stock to the Australopithecines first appearing about four million years ago. The more recent genus Homo is thought to arise about two million years ago and contains sequentially such representatives as Homo habilis, Homo erectus, archaic Homo sapiens, the Neanderthals, the Cro-Magnons, and finally modern man, sometimes designated as Homo sapiens sapiens. Evolutionists reject the notion of a single first true human being. They view human emergence as a gradual process of becoming more intelligent, more self-reflective, and more capable of consciousness – a process called “hominisation.” Clearly, this evolutionary perspective rejects the notion of a single set of first parents.

But man’s intellective soul does not admit of “gradual emergence.” It cannot be only “partially” existent, since between being and non-being there is no middle. The intellect’s exercise may be diminished or even extinguished through brain deficiency or injury, but intellect itself is fully present in every true man.

Fossil skeletal remains do not reveal intellective presence, only reliable evidence of controlled use of fire or intellectively produced artifacts do. Since all signs of controlled use of fire are controversial prior to 150,000 years ago, much older artifact evidence determines the first human presence in the paleological record. I propose that the first unequivocal evidence of intellective activity is found in congruent, three-dimensionally symmetrical later Acheulean stone tools (hand axes). Paleoanthropologists date these to the Middle Pleistocene period – about half a million years ago. Although he might not embrace my philosophical inferences, the hand ax data I describe here is consistent with the empirical findings of anthropologist Thomas Wynn (“Archeology and Cognitive Evolution,” Behavioral and Brain Sciences, June 2002). The time line for these sophisticated Acheulean hand axes would associate them with the later Homo erectus population, merging into archaic Homo sapiens. Genuine human beings might have existed earlier, and perhaps we will one day find uncontroversial evidence of their presence, for example, if we were to find even more ancient cave drawings or artistic tools.

Admittedly, stone hand axes exhibiting primitive symmetry date back about 1.4 million years to early Homo erectus. Still, recall that birds can select twigs and straw that they instinctively deem fitting for nest-building, and Goodall’s chimps can pick and fashion grass reeds proper for termite-fishing – without thereby manifesting true intellect. Early Homo erectus might well have learned through practical experience to fashion rudimentary hand axes with some symmetry, conditioned by their environment to produce tools so shaped for pure utility, such as the need to cut flesh off dead animals. Wynn tells us that such shape-recognition abilities are not beyond the capability of apes. As seen above, apes fail to manifest evidence of intellective ability.

What is peculiar about the Middle Pleistocene sophisticated hand axes of later Homo erectus is that they are not only useful, but aesthetic. They are perfected on all sides, requiring the maker to conceive the geometrical properties on the unseen side that he seeks to perfect on his “working” side. This requires an intellective grasp of geometry and proportion exceeding mere sensible imagination. These half-million-year-old hand axes appear to offer the first unequivocal evidence of genuine intellective activity, indicating the presence of true man with a spiritual intellective soul. Could this then be the population in which Adam appears?

Indeed, later Homo erectus provides an apt subject for such speculation. In height, he averages five-feet-ten-inches tall, and is far more similar anatomically to modern man than any earlier proposed hominids, such as the immediately preceding and much shorter Homo habilis. The Homo erectus cranial capacity ranged from 775 to almost 1,300 cubic centimeters. Some, especially later ones, had larger brains than many people today. While Homo erectus first appeared some two million years ago, recall that the criteria evincing intellective presence does not appear until the Middle Pleistocene period, half a million years ago. If true, something radical happened within this population, transforming it from merely highly sophisticated brute animals into true human beings with spiritual souls.

One cannot overestimate the importance of finding the proper “line of demarcation” between subhuman primates and true man in the quest for Adam and Eve. On the assumption that the current human-evolution theory is essentially correct, such a demarcation line must exist, since we know philosophically that (1) human intellective powers are irreducibly superior to animal sense powers, and (2) the human spiritual soul cannot emerge gradually. Either a given primate is true man or not. Either a spiritual soul is present or not. Some primate must be the first true man, wholly and completely, all at once – even if the fossil and paleological record fails to reveal that critical point of occurrence in time and place.

Most evolutionists maintain that man is merely a highly developed animal, differing from lower animals in complexity, but not in kind. Naturalistic animal psychologists expect subhuman primates to approach human beings’ mental powers. For them, there really is no first genuinely human being, no Adam. In the other extreme, some Christians, such as astronomer Hugh Ross, trying to defend modern man’s role in Genesis as unique, deny true humanity even to the Neanderthals. Recent cultural evidence has shown that the Neanderthals were true men, possessing symbolic artifacts, burying the dead with religious meaning, and so forth. Still, the fact that there could be doubts about the cultural status of true humans who flourished as little as 32,000 years ago supports my reading of later Homo erectus as possessing intellective souls. The absence of extensive signs of human culture in this Middle Pleistocene population may prove nothing except the fact that those rugged stone hand axes may be the only artifact that easily survives to the present day. Or, as happened with the Neanderthals, further signs of human culture among these later Homo erectus populations may eventually be discovered. Still, does the hypothesized first true man of that Middle Pleistocene population fit the depiction of Adam found in Genesis?

Many are scandalized when they compare the Genesis account to that of the current evolutionary theory and discover what appears to be clearly deviant chronology. Suggesting that the first man might have lived as early as 500,000 years ago appears to fly in the face of the patriarchal genealogy found in Genesis. Genesis 5 and 11 give the genealogies from Adam to Abraham. Adam was 130 years old when he “begot” Seth. Seth begot Enos when he was 105. Enos begot Kenan when he was 90, and so forth. The genealogy gives the age of each patriarch when he begot his offspring, until, finally, Terah begot Abram (Abraham) when he was 70. Added together, the sum from Adam to Abraham is just over 2,000 years. Since we know the time from Abraham to Christ was a little less than 2,000 years, the total time from the present back to Adam must be about 6,000 years – certainly not 500,000 years! The chronology problem appears insurmountable.

But it isn’t. “Begot” need not imply immediate generation of a son or daughter. Matthew 1:8 reads: “And Joram begot Uzzi'ah.” It turns out that Uzzi'ah is not Joram’s son, but his great-great grandson! The most striking case of a genealogy leaving out intermediate names, even where sonship appears explicitly stated, is Matthew 1:1 which reads: “Jesus Christ, the son of David, the son of Abraham.” Most reputable scholars today recognize that the patriarchal genealogies of Genesis give no information as to the true age of mankind, whether it be six thousand or six million years.

The Catechism of the Catholic Church (#390) tells us how to read Genesis: “The account of the fall in Genesis 3 uses figurative language, but affirms a primeval event, a deed that took place at the beginning of the history of man.” As a rigorous standard against which to test the Homo erectus hypothesis proposed above, Origin of the Human Species uses the decisions of the 1909 Biblical Commission. Some of those findings, such as the original happiness of Adam and Eve in a state of justice, integrity, and immortality, the command of obedience, the sin and fall from the state of innocence, and the promise of the Redeemer are not such as to be verifiable in the fossil record or testable against evolution theory. More problematic are the teachings about the special creation of the man, the formation of the first woman from the man, and the unity of the human race.

The “unity of the human race” affirms the teaching of theological monogenism, meaning that from a single pair of first parents, Adam and Eve, all true human beings descended. Pius XII’s encyclical Humani Generis explicitly rejects the opposing theory of theological polygenism, which maintains that Adam represents a number of individuals who act as first parents, or that after Adam, true men lived on Earth who were not his natural descendants. The “unity of the human race” is what might be called an “indirect” dogma, since it is necessarily presupposed by the doctrine of Original Sin, which affirms that it is a sin committed by an individual man and is a quality found in all men because it has been handed down by descent from Adam. How can monogenism, in its theological meaning of a single pair of first parents, be held in light of evolution theory?

Modern anthropologists use the terms “monogenism” and “polygenism” differently than do Catholic theologians. Today’s anthropologists often mean by “monogenism” that all human races have their origin in a single human species, and by “polygenism” that the races have separate origins. “Monogenetic” can mean just one type, or population, and not necessarily just a single pair of first parents.

Most evolutionists speak in terms of evolving populations, not evolving individuals. They might allow that evolution could pass through a “bottleneck” of a single mating pair, but would insist that such an event is improbable. Today’s major contending theories about human origins are (1) the dominant “single-origin hypothesis,” sometimes called the “Out-of-Africa model” or “replacement hypothesis,” supported by such paleoanthropologists as Donald Johanson and Ian Tattersall, and (2) the presently less-favored “multiregional hypothesis,” whose chief proponent is anthropologist Milford H. Wolpoff. While the “single-origin hypothesis” may entail the modern anthropological meaning of “monogenism,” the fact remains that none of these contending theories envision that we descended from a single pair of first parents. Moreover, both theories maintain that Homo erectus had spread to distant lands long before the Middle Pleistocene period, when the hypothesized Adam would have appeared. Nonetheless, theological monogenism remains plausible, since God has no problem overcoming “improbability.” Evolutionist Teilhard de Chardin points out in his Phenomenon of Man (1959), “At those depths of time when hominisation took place, the presence and the movements of a unique couple are positively ungraspable, unrevealable to our eyes at no matter what magnification.”

Hidden in prehistory’s distant recesses, the radical step from merely sentient animal to intellectively souled man constitutes the creation of a new and higher natural species, but not necessarily a discernible change in morphology. Paleoanthropology would never discover its exact time or place. This new, truly human, primate species might mate only within itself either by natural repugnance to intimate relations with subhuman primates, or through some other indiscernible natural or divinely ordered mechanism of reproductive isolation. Over many thousands of years, this new truly human species, though morphologically almost indistinguishable from older subhuman hominids, might gradually replace them in virtue of its intellective superiority – leaving no evidence of the earlier form’s extinction. The scientist notes only wide geographic distribution of the newer artistic form of hand ax, as well as other signs of behavior unseen before, such as hunting, not just scavenging, of large animals, and an early form of hunter-gathering.

Respecting the “special creation of man,” nothing prevents God from directly creating Adam from the “slime of the earth” in most literal biblical manner, an event totally escaping modern scientific observation. Still, Cyril Vollert suggests in his Symposium on Evolution (1959) that evolution theory might integrate with Scripture if God directly infused the human spiritual soul into a fully adult subhuman primate. Such transformation would instantly change the entire material organization of that primate into true man. Vollert also proposes that this radical change might have taken place at the embryonic level. In that case, subhuman primates would not be the real parents of Adam, since his direct creation as a human being, though using evolved embryonic material principles, would be the work of God, who alone can create the spiritual human soul as well as raise matter to the level of this qualitatively higher new species. Even subhuman primates might readily rear such “offspring” as their own. This new species could then separate from the prior subhuman stock in the manner described above.

The “formation of the first woman from the man” poses a greater challenge, if we are to take an evolutionary perspective and attempt a real material connection to Adam. Again, God could have taken Eve from an adult Adam’s rib in most literal fashion. Still, since the Hebrew word sela can also mean “side,” a more creative, evolutionary scenario might be proposed – one based on Vollert’s hypothesis of embryonic transformation. Monozygotic twinning might have occurred immediately following Adam’s formation. Save in the rarest of instances, such twinning produces siblings of the same sex. God might have foreordained that an almost unique "XXY" zygote form monozygotic boy/girl twins by one of the twins dropping the extra "X" chromosome and the other twin dropping the extra "Y" chromosome. Or else, by unseen direct divine intervention, a “Y” chromosome is changed into an “X” chromosome in the twin that becomes Eve. In the miracle of the Virgin Birth in which Mary begets her Divine Son, it appears that an “X” chromosome must have been transformed into a “Y” chromosome -- in order that a male Savior be born. The process of begetting Eve might have entailed a “reverse” foreshadowing of the miracle that was to bring mankind its Redeemer.

Some of these speculations that attempt to reconcile current human evolution theory with authoritative Church interpretation of Genesis challenge the imagination. Still, Origin of the Human Species offers what may be the most detailed effort to fulfill that task without offending science, reason, or Scripture. Some may prefer other alternatives, such as (1) rejecting evolution in favor of young-earth creationism, or (2) raising the possibility that anatomically modern humans might have been contemporaries of their supposed evolutionary ancestors. Michael A. Cremo and Richard L. Thompson’s book Forbidden Archeology (1993) documents evidence of this latter alternative. The present enquiry does not seek to address the merits of these other proposals.

Adam and Eve’s historical reality remains an essential preamble to Christian faith. The preceding philosophical analysis of current human evolutionary theory’s interface with legitimate scriptural interpretation demonstrates that intelligent, well-educated, reasonable Christians even today have good cause to believe those fundamental truths revealed by God in the first three chapters of Genesis.